C. Data is stored in solid-state flash memory which is protected in a crash-hardened case located in the forward area of the recorder.
D. The FDR contains its own internal power supply for converting the +28 V airplane power to the necessary regulated voltages.
E. Underwater Locator Beacon
(1)
An Underwater Locator Beacon (ULB) is mounted on the front panel of FDR. The ULB aids in location of a submerged FDR.
(2)
The ULB is a battery-powered device which radiates a pulsed acoustic signals into surrounding water upon activation by its water-sensitive switch.
(3)
The ULB is contained in a cylindrical watertight case designed to withstand high impact shock and deep water immersion.
(4)
It operates continuously for at least 30 days after being immersed. It will withstand depths to 20,000 feet and has a detection range of 6,000 to 12,000 feet, depending on the sea conditions.
4. Accelerometer (Fig. 1)
_____________
A. The three-axis accelerometer measures vertical, lateral, and longitudinal acceleration and provides a separate output signal referenced to ground for each. Excitation for the accelerometer is 28 volts dc from the FLT REC DC circuit breaker on the P180 DC Power Distribution Panel. The accelerometer is mounted on a bracket, near the airplane's center of gravity, on the inboard wall of the right body gear wheel well.
5. Operation (Fig. 2 and 3)
_________
A. Functional Description
(1)
The flight data recorder system automatically provides a record of selected airplane operating parameters for a 25-hour period.
(2)
Airplane flight data is received by the DFDAC from the left, center, and right EIU's on ARINC 429 data bus. The left EIU has a priority, data from the left EIU is normally sent to DFDAC. If the left EIU fails, the center EIU will send the data to DFDAC. If data from the center EIU is not available, data from the right EIU will be used by DFDAC.
(3)
The DFDAC also receives the acceleration analog data from 3-axis accelerometer and radio keying discrete signals from HF and VHF communications systems.
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747-400
MAINTENANCE MANUAL
115V AC
FLT RCDR AC
ARINC 717
ARINC 717 L-EIU
DIGITAL FLIGHT DATARECORDER
C-EIU
EIU-R-C-1PROGRAMPIN PLUG R-EIU3-AXIS ACCELEROMETER SATCOM SDU
MODE CONTROL
PANEL
GND L-VHF
AIR
PRIMARY AIR/GND RELAY
C-VHFMAWEA PWR A
115V AC
115V AC R-VHFMAWEA PWR B P7
ARINC 429L-HF L-CMC
DMU DIGITAL FLIGHT DATA ACQUISITION CARD
ARINC 429
R-HF
R-CMC MAWEA CARD FILE
Flight Data Recorder System Block Diagram
Figure 2
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M49692
A
747-400
MAINTENANCE MANUAL
B579 RCDR-DIGITAL FLIGHT DATA (E8)
M7952 MAWEA CARD FILE STA 360, WL 140, RBL 35
Flight Data Recorder System Schematic DiagramFigure 3
C82138
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(4)
The DFDAC collects, conditions, and multiplexes the parameter signals into a serial binary data stream. The serial data stream is output to the FDR in a continuous four-second data frame. The output data stream consists of four subframes each having 64 12-bit words.
(5) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 指示/记录系统 1(47)
